The attribution Powered by Blogger is normally stay locked, Which can not be removed at all. Some custom templates also keeps it locked. But some people does not like it. They want to remove the attribution from their favorite blog or site. This can be done by editing the html code.
The attribution can be removed or deleted by the following methods.
>>> First Login to your blogger account
>>> Go to Template
>>> Click Edit HTML
>>> Click any place of the code area & Press Ctrl+F and Write attribution in the search area.
>>> Now just replace the true with false
>>> Now Click Save Template
Now you can remove the Powered by Blogger attribute from layout menu.